Process for the continuous manu



Patented Apr. 30, 1935 UNITED STATES PATENT OFFICE PROCESS FOR THE CONTINUOUS MANU- FACTURE OF AI'VHHONIUM SALTS Arthur Ferdinand August Reynhart, Velsen- Noord, Netherlands, assignor to Naamlooze impure colour of the salts manufactured from ammonia and acids must be principally ascribed colour of the salt, and on various working conto the presence of iron and small quantities of dltions. arsenic due to impurities in the acid used, Con- Another embodiment of the proc s according centrations of 0.02% iron in the salt have already t y invention Consists in a p Of the liquid in a very noticeable effect on the colour of the salt. the saturator being continuously drawn off, neu- It has now been found that in the continuous tralized and, after the pre has been manufacture of ammonium salts from ammonia moved, returned to the saturator. and acids a white or practically white salt can It is also possible according to the invention be obtained by neutralizing the whole or part of to keep the content of those components of the 30 the acid liquid used and removing the precipitate acid that are injurious to the colour of the amformed thereby, after which the filtered liquid monium salts at the desired low level by wholly can again be used in the continuous manufacture. or partly, continuously or periodically neutral- A practical embodiment of the process is as Zing the mother lye obtained from the separafollows: tion of the crystals, before this is returned to 35 Sulphuric acid of the desired conciiintration, the saturator, and removing the precipitate- It e. g 8 to 10%, is put in a saturator, ammo i is therefore possible to collect, for instance, the is then continuously admixed with the sulphuric mfithel y 0f the Centrifuge-3i 0 if fi t a acid, the solid ammonium sulphate forming bcused, the filtrate, either continuously or perioding run oil from the saturstor by means of an ically in a tank and, if necessary after being ejector, and then freed of the greater part of the dilu d With water, n lize i wi h mmonia acid liquid. first in collecting tanks and afterand filter it, after which the filtrate is returned Wards in centrifuges. The mother lye thereby $0 th atH ELt obtained is returned to the saturator, The moist In the Same Way it is Possible to treat the salt is subsequently dried with hot air and ncuthe liquid wining fI'Om the pp a iralized with ammonia. cumulating tanks and any other vessels between 7 It is clear that the concentration of the colourthe saturator and. the centrifuge (filter). ing components. in this and As. .COlllCS What I claim is: continually greater in the satui'ator. so that at a 1, In the process of making ammonium sulfate given moment it becomes so large that the colour by passing ammonia into a bath of sulfuric acid 0f the p e I10 longer p the normally containing as impurity iron, and re- N0 Drawing. Application February 12, 1931,

Serial No. 515,420.

In the Netherlands Februany 24, 1930 3 Claims. (Cl. 23-119) My invention relates to a process for the conquirements. The contents of the saturator are tinuous manufacture of ammonium salts from ammonia and acids.

The object of the invention is to arrange the method of manufacturing ammonium salts, for instance sulphate, nitrate, phosphate, chloride, etc., in such a way that the colour of the product is completely under control.

It is known that the ammonium sulphate. manufactured for instance, from synthetic ammonia and technical sulphuric acid has a yellow or cream colour. Absolutely white ammonium sulphate has been obtained so far, for instance, by a double conversion of a suspension of gypsum with a solution of ammonium carbonate, the mass being then filtered, after which pure white ammonium sulphate is obtained from the solution by evaporation.

From investigations it has been found that the then entirely neutralized with ammonia, and filtered, as a result of which the Fe and As present are removed. The filtered liquid is then again suitable for use in the saturator. This can be brought about by siphoning over the liquid from the saturator into a tank in which, after water has been added, if necessary, to prevent crystallization, neutralization is carried out with a small excess of NH2, after which the neutralized liquid is filtered and returned to the saturator. The moment at which the neutralization and filtration of the contents of the saturator is carried out, depends of course on the purity of the sulphuric acid, whereby it may also be necessary to take into account the possibility that the sulphuric acid may contain impurities through corrosion of some parts of the apparatus. Further the moment at which the neutralization takes place depends on the requirements made of the moving solid ammonium sulfate from said bath, that improvement in producing said ammonium sulfate free from discoloration which comprises withdrawing and treating at least a portion of said acid bath with ammonia to neutralize the acid and to precipitate the coloring contaminants, removing from the resulting neutralized liquor the precipitate formed, and returning the neutralized liquor to the acid bath.

2. In a process of making ammonium sulfate by passing ammonia into a bath of sulfuric acid normally containing d'iscolorants, that improvement in producing said ammonium sulfate free from discoloration which comprises withdrawing and treating at least a portion of said acid with ammonia to neutralize the acid and to precipitate the discolorants, removing the precipitate formed and returning the neutralized liquor to the acid bath.

3. In the process of making ammonium sulfate by passing ammonia into a bath of sulfuric acid normally containing as impurity arsenic and removing solid ammonium sulfate from said bath, that improvement in producing said am monium sulfate free from discoloration which comprises withdrawing and treating at least a portion of said acid bath with-ammonia to neutralize the acid and to precipitate the coloring contaminants, removing from the resulting neutralized liquor the precipitate formed, and returning the neutralized liquor to the acid bath ARTHUR FERDINAND AUGUST REYNHART. 

